Method for forming trench isolation

Abstract

A method for forming a trench isolation is disclosed, comprising, providing a substrate comprising a trench, forming a polysilicon layer in the trench, and subjecting the substrate to a treating process to convert the polysilicon layer to an isolating layer, wherein the treating process is fine tuned for the isolating layer on opposite sidewalls of the trench to expand to contact with each other so that the isolating layer fills the trench.

1 . A method for forming a trench isolation, comprising:
 providing a substrate comprising a trench;   forming a polysilicon layer in the trench; and   subjecting the substrate to a treating process to convert the polysilicon layer to an isolating layer, wherein the treating process is fine tuned for the isolating layer on opposite sidewalls of the trench to expand to contact with each other so that the isolating layer fills the trench.   
     
     
         2 . The method for forming a trench isolation as claimed in  claim 1 , wherein the treating process is an oxidation treating process. 
     
     
         3 . The method for forming a trench isolation as claimed in  claim 1 , wherein the treating process is a nitridation treating process. 
     
     
         4 . The method for forming a trench isolation as claimed in  claim 1 , wherein the trench has a width of less than 15 nm. 
     
     
         5 . The method for forming a trench isolation as claimed in  claim 1 , wherein the isolating layer is made of silicon oxide. 
     
     
         6 . The method for forming a trench isolation as claimed in  claim 1 , wherein the isolating layer is made of silicon nitride. 
     
     
         7 . The method for forming a trench isolation as claimed in  claim 1 , wherein a mask layer is formed on the substrate and the step of forming the polysilicon layer further forms the polysilicon layer on the mask layer. 
     
     
         8 . The method for forming a trench isolation as claimed in  claim 7 , wherein the mask layer is made of silicon nitride. 
     
     
         9 . The method for forming a trench isolation as claimed in  claim 1 , wherein the process condition of the treating process is fine tuned so that the isolating layer fills the trench with substantially no seams therein. 
     
     
         10 . The method for forming a trench isolation as claimed in  claim 7 , further comprising removing the mask layer and the isolating layer outside of the trench. 
     
     
         11 . The method for forming a trench isolation as claimed in  claim 1 , wherein the substrate comprises active areas and the treating process is fine tuned for the substrate in the active area to not be consumed by the treating process. 
     
     
         12 . A method for fabricating a semiconductor device, comprising:
 providing a substrate comprising a trench;   forming a polysilicon layer in the trench; and   subjecting the substrate to a oxidation process to convert the polysilicon layer to a silicon oxide layer, wherein the treating process is fine tuned for the silicon oxide layer on opposite sidewalls of the trench to expand to contact with each other so that the silicon oxide layer fills the trench; and   removing the silicon oxide layer outside of the trench.   
     
     
         13 . The method for fabricating a semiconductor device as claimed in  claim 12 , wherein the trench has a width of less than 15 nm. 
     
     
         14 . The method for fabricating a semiconductor device as claimed in  claim 12 , wherein a mask layer is formed on the substrate and the step of forming the polysilicon layer further forms the polysilicon layer on the mask layer. 
     
     
         15 . The method for fabricating a semiconductor device as claimed in  claim 12 , wherein the mask layer is made of silicon nitride. 
     
     
         16 . The method for fabricating a semiconductor device as claimed in  claim 15 , further comprising removing the mask layer outside of the trench. 
     
     
         17 . The method for fabricating a semiconductor device as claimed in  claim 12 , wherein process condition of the treating process is fine tuned so that the isolating layer fills the trench with substantially no seams therein. 
     
     
         18 . The method for fabricating a semiconductor device as claimed in  claim 12 , wherein the substrate comprises active areas and the oxidation process is fine tuned for the substrate in the active areas to not be consumed by the oxidation process. 
     
     
         19 . The method for fabricating a semiconductor device as claimed in  claim 12 , wherein the oxidation process is wet oxidation process. 
     
     
         20 . The method for fabricating a semiconductor device as claimed in  claim 12 , wherein the oxidation process has a temperature of 700° C.-1000° C.